Ragweeds are flowering plants in the genus Ambrosia in the aster family, Asteraceae. They are distributed in the tropical and subtropical regions of the Americas, especially North America, where the origin and center of diversity of the genus are in the southwestern United States and northwestern Mexico. Several species have been introduced to the Old World and some have naturalized and have become invasive species. Ragweed species are expected to continue spreading across Europe in the near future in response to ongoing climate change.
Helianthus is a genus comprising about 70 species of annual and perennial flowering plants in the daisy family Asteraceae commonly known as sunflowers. Except for three South American species, the species of Helianthus are native to North America and Central America. The best-known species is the common sunflower. This and other species, notably Jerusalem artichoke, are cultivated in temperate regions and some tropical regions, as food crops for humans, cattle, and poultry, and as ornamental plants. The species H. annuus typically grows during the summer and into early fall, with the peak growth season being mid-summer.
Ambrosia trifida, the giant ragweed, is a species of flowering plant in the family Asteraceae. It is native to North America, where it is widespread in Canada, the United States, and northern Mexico.
Eriodictyon capitatum, the Lompoc yerba santa, is a rare evergreen shrub in the borage family. It is endemic to western Santa Barbara County, in California.
Erysimum menziesii is a species of Erysimum known by the common name Menzies' wallflower.
Ambrosia pumila is a rare species of herbaceous perennial plant known by the common names San Diego ragweed and San Diego ambrosia. It is native to far southern California, Baja California, and Baja California Sur. It grows in floodplains and open grasslands in proximity to wetland areas.
Ayenia limitaris is a rare North American species of flowering plant in the mallow family known by the common names Rio Grande ayenia, Texas ayenia, and Tamaulipan kidneypetal. It is native to an area straddling the Rio Grande in Mexico and the United States. Today it is known from far southern Texas and far northern sections of the Mexican states of Coahuila and Tamaulipas. It has become rare because most of its habitat has been degraded or destroyed. There are perhaps four populations remaining in Texas and two in Mexico, for a total of 1000 individual plants at most. It is a federally listed endangered species of the United States.
Cirsium vinaceum is a rare species of thistle known by the common name Sacramento Mountains thistle. It is endemic to Otero County, New Mexico, in the United States, where it is known only from the Sacramento Mountains. The plant can be found in six canyon systems in a southern section of this mountain range spanning about 32 kilometers. It is rare because it is limited to a specific type of mountain wetland which is both naturally uncommon and threatened by a number of forces. The plant was federally listed as threatened in 1987.
Coryphantha ramillosa is a rare species of cactus known by the common names bunched cory cactus and whiskerbush. It is native to the border region between Texas in the United States and Coahuila in Mexico. Because it was believed to be rare and threatened by a number of processes, it was federally listed as a threatened species of the United States in 1979.
Pelecyphora sneedii is a rare species of cactus known by the common names Sneed's pincushion cactus and carpet foxtail cactus.
Echinocereus viridiflorus is a species of cactus known by the common names nylon hedgehog cactus, green pitaya, and small-flowered hedgehog cactus. It is native to the central and south-central United States and northern Mexico, where it can be found in varied habitat types, including desert scrub, woodlands, dry grasslands, and short-grass prairie.
Eriogonum gypsophilum is a rare species of wild buckwheat known by the common names Seven River Hills buckwheat and gypsum wild buckwheat. It is endemic to the state of New Mexico in the United States, where it is known from only three sites in Eddy County. It is limited to a specific type of soil which is high in gypsum. The plant has been federally listed as a threatened species of the United States since 1981.
Hoffmannseggia tenella is a rare species of flowering plant in the legume family known by the common name slender rushpea. It is endemic to Texas, where it is known from only two counties. It persists in small remnants of its gulf coastal prairie habitat. It is a federally listed endangered species of the United States.
Hymenoxys texana is a rare species of flowering plant in the aster family known by the common names prairie dawn, Texas prairie dawn-flower, and Texas bitterweed. It is endemic to Texas, where it is known only from the general vicinity of Houston. It is threatened by the loss of its habitat. It is a federally listed endangered species of the United States.
Packera franciscana is a rare species of flowering plant in the aster family known by the common name San Francisco Peaks groundsel, or San Francisco Peaks ragwort. It is endemic to Arizona in the United States, where it is known only from the San Francisco Peaks in Coconino County. It is threatened by recreational activities in its habitat. It is a federally listed threatened species of the United States.
Solidago houghtonii is a rare North American species of flowering plant in the family Asteraceae known as Houghton's goldenrod. It is native to southern Ontario, Canada and the northern United States. It is threatened by the loss and degradation of its habitat. It is a federally listed threatened species of the United States and it is designated a species of special concern by Canada's Committee on the Status of Endangered Wildlife in Canada.
Spiranthes delitescens is a rare species of orchid known by the common names reclusive lady's tresses, Canelo Hills lady's tresses, and Madrean lady's tresses. It is native to Arizona in the United States, where there are only four occurrences. It is threatened by the loss and degradation of its habitat. It is a federally listed endangered species of the United States.
Thymophylla tephroleuca is a rare species of flowering plant known by the common names ashy pricklyleaf and ashy dogweed. It is endemic to Texas in the United States, where it occurs in two counties near the Mexican border. It became rare due to the destruction and degradation of its habitat. It is a federally listed endangered species of the United States.
Ambrosia linearis is a species of flowering plant in the family Asteraceae known by the common names streaked bur ragweed, Colorado bursage, linear-leaf bursage, and plains ragweed. It is endemic to east-central part of the state of Colorado in the United States, where it occurs in Elbert, Pueblo, El Paso, Cheyenne, Crowley, Kiowa and Lincoln Counties.
Eriogonum visheri is a species of wild buckwheat known by the common names Dakota wild buckwheat and Visher's buckwheat. It is native to the Great Plains in the United States, where it is known from North Dakota, South Dakota, and Montana.
